Voice user interfaces are provided to allow a user to interact with a system using their voice. One advantage of this, for example in devices such as smartphones, tablet computers and the like, is that it allows the user to operate the device in a hands-free manner.
In one typical system, the user wakes the voice user interface from a low-power standby mode by speaking a trigger phrase. Speech recognition techniques are used to detect that the trigger phrase has been spoken and, separately, a speaker recognition process is used to confirm that the trigger phrase was spoken by a registered user of the device.
The voice user interface may then provide a prompt to the user, to confirm that the system is active, and the user may then speak a command, which can be recognised by the voice user interface using speech recognition techniques.
The voice user interface may then act on that spoken command. For example, if the spoken command asks for publicly available information, the spoken command may be recognised, and used to generate a query to an internet search engine in order to be able to supply that information to the user.
However, in other cases, for example if the spoken command relates to personal information, the level of authentication provided by the speaker recognition process may be considered insufficient for the voice user interface to act on that command. In such cases, the user may be asked to provide an additional form of authentication, for example by entering a PIN number or password through a keypad of the device, or by providing additional biometric authentication, such as a fingerprint scan.
This means that the user is no longer able to operate the device in a hands-free manner.